Last checked at 
* Trial to start by the end of the year - Russia's RDIF
* Boost for Russian vaccine, which has been criticised in
West
* Once COVID-19 vaccine frontrunner, AstraZeneca has slipped
back
(Updates with Russian defence ministry comment, edits)
By Andrew Osborn and Pushkala Aripaka
Dec 11 (Reuters) - AstraZeneca is to start clinical trials
to test a combination of its experimental COVID-19 vaccine with
Russia's Sputnik V shot to see if this can boost the efficacy of
the British drugmaker's vaccine, Russia's sovereign wealth fund
said on Friday.
Trials will start by the end of the year and Russia wants to
produce the new vaccine jointly if it is proven to be effective,
said the RDIF wealth fund, which has funded Sputnik V.
AstraZeneca said it was considering how it could assess
combinations of different vaccines, and would soon begin
exploring with Russia's Gamaleya Institute, which developed
Sputnik V, whether two vaccines based on a common-cold virus
could be successfully combined.
It did not give further details. However, its Russian arm
said it would start to enrol adults aged 18 and older for the
trial.
The cooperation between one of Britain's most valuable
listed companies and the state-backed Russian research institute
highlights the pressure to develop an effective shot to fight
the pandemic, which has killed over 1.5 million people.
The move is likely to be seen in Moscow as a long-awaited
vote of confidence by a Western manufacturer in Sputnik V, which
the Russian defence ministry alleged on Friday was the target of
a foreign-backed smear campaign.
Sputnik's Russian developers say clinical trials, still
under way, have shown it has an efficacy rate of over 90%,
higher than that of AstraZeneca's own vaccine and similar to
those of U.S. rivals Pfizer and Moderna.
Some Western scientists have raised concerns about the speed
at which Russia has worked, giving the regulatory go-ahead for
its vaccines and launching large-scale vaccinations before full
trials to test Sputnik V's safety and efficacy have been
completed. Russia says the criticism is unfounded.
AstraZeneca, once seen as a frontrunner in the vaccine race,
is preparing further tests to confirm whether its shot could be
90% effective, potentially slowing its rollout.
Its average efficacy rate was 70.4% in interim late-stage
data - which prompted the developers of Sputnik V to suggest
trying to combine the two vaccines.
TWO VACCINES BETTER THAN ONE?
RDIF head Kirill Dmitriev called AstraZeneca's acceptance of
the proposal "an important step towards uniting efforts in the
fight against the pandemic".
Kate Bingham, chair of Britain's vaccine task force, said
this week that the UK would start trials next year using
combinations of different kinds of vaccine for the initial and
booster vaccinations, in the hope that a "mix-and-match"
approach might maximise the immune response.
Both projects are using harmless adenoviruses as vehicles,
or vectors, to carry genetic instructions into the body to
prompt cells to produce antibodies, an approach that has
previously been used in an Ebola vaccine.
One challenge of such a method is that the immune system
could attack the vector and, in particular, neutralise the
second booster shot that is now an important feature of the
leading COVID-19 vaccine candidates.
Using different viral vectors for the two shots is one
approach that researchers, including at the Gamaleya Institute,
have pursued. Combining vaccines from different developers could
be another.
AstraZeneca did not mention immunity against the viral
vector as an issue in its statement on Friday.
The firm and its partner Oxford University have used a
harmless adenovirus found only in monkeys to ensure that people
receiving the shot had not previously been exposed to the vector
and developed an immune response against it.
Russian officials have not always been complimentary about
the British vaccine.
When AstraZeneca paused a clinical trial in September due to
the unexplained illness of a volunteer, Kremlin spokesman Dmitry
Peskov told reporters that Sputnik V was more reliable because
it was based on an adenovirus found in humans, whereas the
British candidate was a "monkey vaccine".
The new partnership may draw scrutiny after Britain said in
July that hackers backed by the Russian state were trying to
steal COVID-19 vaccine and treatment research from academic and
pharmaceutical institutions around the world. The Kremlin
rejected the allegations.
(Reporting by Pushkala Aripaka in Bengaluru and Andrew Osborn
in Moscow; Additional reporting by Ludwig Burger
Writing by Josephine Mason;
editing by Patrick Graham, Mark Potter and Kevin Liffey)
